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Test Description

The numbers below refer to the step numbers in the diagnostic table.

  1. 2:  If the engine starts and DTC P1628 resets, there is a condition with the theft deterrent detection coil or the ignition key transponder, continue diagnosis in theft deterrent.
  2. 3:  This step tests for ignition voltage to the theft deterrent module. The theft deterrent module cannot communicate with the ECM if there is no ignition positive voltage.
  3. 4:  This step tests for a good ground to the theft deterrent module. The theft deterrent module cannot communicate with the ECM if there is no ground circuit.
Step Action Yes No
Schematic Reference: Theft Deterrent System Schematics
Connector End View Reference: Theft Deterrent System Connector End Views
1 Did you perform the Diagnostic System Check - Engine Controls? Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 
  1. Turn ON the ignition, with the engine OFF.
  2. Clear the DTCs with a scan tool.
  3. Attempt to start the engine.
Does the engine start and idle?		 Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the theft deterrent module electrical connector.
  3. Turn the ignition ON, with the engine OFF.
  4. Connect a test lamp between the Ignition 1 voltage circuit of the theft deterrent module and ground.
Does the test lamp illuminate?		 Go to Step 4  Go to Step 6 
4  Connect a test lamp between the ground circuit of the theft deterrent module and B+.
Did the test lamp illuminate?		 Go to Step 5  Go to Step 7 
5 Test for an intermittent and for a poor connection at the theft deterrent control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct a condition?		 Go to Step 9  Go to Step 8 
6 Repair the Ignition 1 voltage circuit of the theft deterrent module for an open or short to ground. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.
Did you find and correct a condition?		 Go to Step 9  -
7 Repair the ground circuit of the theft deterrent module for an open. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.
Did you find and correct a condition?		 Go to Step 9  -
8 Replace the theft deterrent control module. Refer to Theft Deterrent Module Replacement .
Did you complete the replacement?		 Go to Step 9  -
9
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Attempt to start the engine.
  4. Observe the DTC information with a scan tool.
Did the engine start and run with no DTC P1628 set?		 System OK Go to Step 2 
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